Reversible hydraulic drive, including follow-up system



Oct. 21, 1952 E. J. POITRAS ETAL 2,614,390

REVERSIBLE HYDRAULIC DRIVE, INCLUDING FOLLOW-UP SYSTEM Filed Jan 11, 1935 8 Sheetsr-Sheet 1 INVEN OBS J optras D. Team THEIR ATTORNEY Oct. 21, 1952 E. J. polTRAs ETAL I, INCLUDING FOLLOW-UP SYSTEM REVERSIBLE HYDRAULIC DRIV- Filed Jan. 11, 1935 8 Sheets-Sheet 2 INVENTORS Eduza/rd J. Poi/bras Jaanes D. Tea/r THEIR ATTORNEY 1952 E. J. POITRAS EI'AL 2,

INCLUDING FOLLOW-UP sYsT M REVERSIBLE HYDRAULIC DRIHV Filed Jan. 11, 1935 8 Sheets-Sheet 5 INVENTOR 5 Edward J Poiimas Jaones DLTea/r BY THEIR ATTORNEY Oct. 21, 1952 E. J. PO ITRAS ETAL REVERSIBLE HYDRAULIC DRIVE, INCLUDING FOLLOW-UP SYSTEM Filed Jan. 11, 1935 8 Sheets-Sheet 4 THEIR AI'I'ORNEY 1 W 3 I I @Ewi? 1. 5g

Oct. 21, 1952 E. .1. POITRAS EI'AL REVERSIBLE HYDRAULIC DRIVE, INCLUDING FOLLOW-CUP SYSTEM 8 Sheets-Sheet 5 Filed Jan. 11, 1935 &

5g Eahm imi sm Baa nuns D. Tea/r Z4259. THEIRATTORNEY a mmw ,R k

Oct. 21, 1952 E. J. POITRAS .ETAL 2,

REVERSIBLE HYDRAULIC DRIVE, INCLUDING ,RQLIJOW-JJP SYSTEM Filed Jan. 11, 1955 QB Sheets-Sheet "7 siAamszzgfl I9 I 155 0 1:5 J 254 201-- A I IVY 1 OUTPUT LWJ INVENTORIi Edam/rd J.Po was I OUTPUT B-YJMD. Tedd 27 THEIR ATTORNEY AAA AAAIL Oct. 21, 1952 E. J. POITRAS ETAL 2,614,390

REVERSIBLE HYDRAULIC DRIVE, INCLUDING-FOLLOW-UP SYSTEM Filed Jan. 11, 1935 8 Sheets-Sheet 8 Jaanes .D.

- THEIR ATTORNEY operate a signahsuch as a dial.

Patented Oct. 21, 1952 REVERSIBLE HYDRAULIC DRIVE, INCLUD- IN G FOLLOW-UP SYSTEM Edward J. Poitras and James D. Tear, Jackson Heights, Great Neck, N. Y., assignors to The Sperry Corporation, a corporation of Delaware Application January 11, 1935, Serial No. 1,290

The invention herein described comprehends a system and mechanism for controlling the velocity and movement of a driven object. While the invention as thus considered has numerous applications, the embodiment described, in its entirety, is particularly useful in the control of ordnance.

Large ordnance pieces are commonly mounted for movement about two axes at right angles to each other, one, the train axis, perpendicular to the foundation on which the gun is mounted and the other, the elevation axis, at right angles thereto. The aiming of a gun for firing upon a target involves a problem the solution of which gives the necessary movement of the gun in elevation and train. The problem varies with the character of the foundation of the gun and the target, the most exacting conditions being encountered in directing, at a moving target, a gun mounted on an unstable platform such as, for example, the deck of a ship. For the solution of these problems, there is now employed director gun fire control mechanism which from certain observed and generated data related to the line of sight to the target constantly determines and transmits the correct setting of the gun in train and elevation. The inherent characteristics of these gun fire controls and the- 19 Claims. (01. 60-53) transmission systems used are such that the power available is little more than enough to the gun elevation and train are usually expressed as angular quantities which are transmitted as signals to the gun turret where operators,

through manually operative controls, effect movement of the gun to direct it in accordance with the signals.

Several attempts have been made to provide automatic mechanisms and systems in which the gun is made to follow the signals in elevation and.

train without the intervention of a human agency. There has not been, heretofore, how- -ever, an automatic system or mechanism available which is satisfactory, particularly for large guns, and it is one of the objects of this invention to produce a satisfactory system for this purpose. In a complete system for synchronizing the movements of a gun with a signal there should be provisions for moving the gun out of synchronism and returning the gun to synchro nism. This is necessary, for example, in order that the gun may assume loading position, or in order that the gun may be prevented from moving beyond the limits of the turret or into positions where if fired it would strike some part of Consequently,

. I): v L

the vessel itself. The accomplishment of these functions in such a system is another object of this invention. A further object of the invention is to provide an automatic system of this type which may, if found desirable, be operated manually and independently of the automatic control.

These and other objects are realized in the embodiment of the invention illustrated in the accompanying drawings in which: V l

Fig. l is a side elevation of the system connected for moving a gun mount in elevation;

Fig. 2 is a plan taken on the line 22 of Fig: 1; Fig. 3 is a fragmentary sectional elevation of the mechanism for operating the tilting box of a hydraulic gear, taken along the irregular line 3-3 of Fig. 2;

Fig. 4 is an end, sectional elevation of the hand control mechanism taken along the irregular line 4-4 of Fig. 2;

Fig. 5 is a side elevation of the same, partly in section taken along the line 5-5 of Fig. 4; Fig. 6 is an enlarged, fragmentary section taken along the line 6-4; of Fig. 2;

Fig. 7 is a sectional elevation of the intermittent gear taken along the line 1--1 of Fig. 2';

. Fig. 8 is an end elevation of the same taken along the line 88 of Fig. 7, the gear shift lever being omitted; M

Fig. 9 is an enlarged plan of the automatic control mechanism for controlling movement 0 the tilting box of the hydraulic gear;

Fig. 10 is a side elevation of the same taken along the line l0--l0 of Fig. 9;

Fig. 11 is a diagrammatic layout of the hydraulic connections; Fig. 12 is a section of a relief and by pass valve; j v

Fig. 13 is a sectional layout. of the valve block; Fig. 14 is a sectional elevation on enlarged scale of a part of the hydraulic control mechanism taken along the line l4l4 of 9;

Fig. 15 is a sectional side elevation of the same,

3 motor I of suflicient capacity to readily move the un mount 2 about its elevation axis 3. The motor is connected to the gun mount through a variable velocity hydraulic transmission or gear 4 of a type well known and illustrated in United States Letters PatentNo. 925,148 granted June 15, 1903 to D. =Wil1iams f or va'riable Speed Gear. 'ss'shteuy, the hydraulic gee'ra includes a hydraulic pump and a hydraulic motor known respectively as the A and B ends. The pump and motor are identical in construction with one I 4 on a shaft 25 which extends through and is journaled in the casing of the hydraulic gear.

The hydraulic operation of the tilting box is effected by controlling the flow of oil under pressure to the cylinder 20 and thereby controlling the actuation of the piston [9. This control is exercised through a valveblock containing an hydraulic power "amplifier which isoperated by a pair of Selsyn receivers 21 and 28 (Figs. 9 and 10), the angular movement of which represents thesignal. Whether the manual or the hydraulic operation'zis'used, the effect is the same. A force is applied through the piston and the connecting rodto the ldracket 24. The force is in a vert'ical;direction"and;effects movement of the tilting box about it's horizontal axis perpendicular -to the longitudinal axis of the tilting box. In

motion of the pump pistons, and the hydraulic ed by the reciprocation of the "ease-S "febifirbbatory "movement of wh h movement converted efi'notor shaft, the sea- I platesiorboxes inclined orf'th fear; ft. Theinclination'fdf "th meter plate isfixed biitthe plate 5, "orf tiltmeter I directly end foftliehydraulic "9 "between hearings "lbaiid "n. whens-gear I2 I is "thus c dntifolled by '"hitihg the"tiltffig boxbf thehydfauhvgfeanfthe dire ion ofmovement of thegumb'i'rigdben'd- 6" en the dir 'whlch the tiltin 'iemoyedfiemuts n utrerdr vertiea station and the speed ofth I w "the inagnitu extent the tilting box 7 is moved from its neu ran position. In-thrs ystem, "the tilting hex ""r'naiy be inov d" manually 613 ;13 draulically, the latter being used fo'r *-the -fautocentral-er the retirement-or the gu m accordance with a signa. The manual' m'ovei rit br the'tutih hex is frre ted threug-h hendwheis' 15am rs which operate through atrain teeters pen a r'a'ck H mounted iipon a r' 'odj l 8 which' 'extn'ds' from a piston r9 nieehehigeu bonncted tdthe tilting box 'e -Fig.3). -The piston l9 finounted in i a cylinder 2I) having a opening in the case of the hydraulic g r; -The iiistori-isprovided 'witha skirt fl -of-le s diameter than the piston which extends d ouh extension or linder and the tiltzb l. ei'ves a*connctingr6d 2'3*"which is piveuredto the piston" =at"one end "and *to a tne other end. The-bracket is an integral art of -the tiltizig box 5 hi h fiounted meshes with the warm 9 and carriesa" 'pinio'n'lil" box ' tion. 7

vehieh ytemgeepenaem tiifeaaed extension: Pwhieh -"is threaded into an either case, there is also a mechanical reference back from the output shaft of the hydraulic gear which acts in opposition to the movement which originated throughth'e control mechanism. This Ireferenc'e "back is 'a restoringxmechanism "-in opposition to the movement er the control mechanism initiatin the .movement -of the tilting box, and its efiect is to return'the itilting box to the neutral position after a; definite movement proportioned to the initiating movement rat the control mechanism. In this wayfthwtotal move- -men't of the gun :is :vpropor tionalvto ":the. move- {inent acting to displace the tilting box :mm zits neutral position. In the hydraulic *acontrol mechanism, there 2 is provided means :for elirm inating lag 'by 'accelerating the; movement o'f ithe igun (to bring I it into positional agreement with the signal during movement of thersignal.

*Both the hydraulic and .the m'anual montrol's are subservient to limit controls. The limit con- :trols act through an -intermittentigear 29 di'ig's. 2, 7 and '8) and when athez-gun reacheslaapredetermined pos'ition the ilimit "control :mechan- -ically= returns the tilting box -'to:=the=-neutral';posi- I Hand control The han'dwheels "f5 and Hi iprovided rot "the manualbontrol' "of the movement "of theg11n are amounted o "the ends er a r shaft 30 "extending through and 'journaled in a frame '3 l on each fhand-Wheel'thre isfa grip, 'l5'a"and 'lfiafiwhich 'is rotatably j mounted "on "the h'arid h'rlil and through whichthe'wheelsmay b'e 'rot'ated. '"Ilie hand wheels are'secured to the shaft allso'that lth'eshaft rotates therewith. 'om'theshert'eoenh betwee'nthe' verticarrrame*merfibers mesa a'fb there ismou'n'te'd abevled-gear a z' 'which 'meshes with a beveled gear--33 secured "on the end of a -"shaft "3'4 extending "through and j'o'urnaied *in transverse frame elements 3Ican Adja- {cent theframe element fld, there s 'm ted on the shaft' '34 a worm 35. "The worm' fl as m casing. skirt" of the pito'n is--l 'iollow' 7"0 gear 10a which meshes with twor bevel zgearsdflu and 42b (Fig.5) which :are =mounted upon tlie -'-spider.. of a sdifie'rential which aspider is secured -to the-shaft 'M :for rotati'on therewith,- ems -ineshing withtherbeveligeais' fla 'iand 12b there for move'ifient about a horizontal axis" isabevelzgear l3 rotatably mounted onthe sliflt m and formed integraLwith a helica1-:gear43c..

The shaft 4l extends through the side: 3 lb ofthe frame and on the. end of! theshaft there is mounted for rotation therewith a spur: gear 44. This latter gearmeshesxwith a gear 45 mounted upon the end of a shaft which extends through a frame 41 mounted on the endof the hydraulic gear. Intermediate the ends of theframe; there is mounted on the shaft: 46 for rotation therewith a pinion 48 which mesheswith'the rack [l on the rod I8. I Assuming that the clutch 39 is engaged,'rota+ tion of the hand-wheels l5 and [6 will effect rotation of the shaft 34 through the bevel gears 32 and 33. Through the worm and worm gear, con,- nection 35 and 36, the'clutch and the spurgear 38 are rotated with the shaft 31. The worm and worm gear form a non-reversible connection, that is, the hand-wheels could not be rotated through the gear 38. Rotation ofthe gear 38 effects, through its connection with the gear 40, rotation of the gear 40a forming one end of the differential; The helical gear 4 3a meshes with a gear 49 which forms a non-reversible gear train, that is, movement of the gear 43 can only be effected by movement of the gear 49. Thus, upon the initial movement of the hand-wheels and rotation of the gear 40a one side of the differential is stationary and rotation of the gear 40a effects a rotational movement of the spider of the differential and consequently of the shaft 4|. Rotation of the shaft 4|, through the gears and at a speed corresponding to the extent of the movement of the tilting box and through its connection with the shaft 8 will cause the gun to move in elevation.

On the shaft 50, there is mounted a, gear 5! which meshes with a gear 52 secured on the end of a shaft 53 running alongside of, and journaled in bearings secured to the hydraulic gear. The shaft 53 extends parallel to the axis of the hydraulic gear and through the frame member 31b. On that end of the shaft 53 which extends through the frame member 3lb, there is mounted a bevel gear 54 (Fig. 5) which meshes with a bevel gear 55 mounted on, and adjacent the lower end of a vertical shaft 56. The vertical shaft 56 is mounted in two thrust bearings 51 and 58 extending from the frame member 31b. The

helical gear 49 is mounted on the upper end of the shaft 56. Through this train of shafts and gears, the gear 49 is rotated in accordance with the rotation of the shaft of the B end of the hydraulic gear. Rotation of the gear 49 effects rotational movement of the gear 43a, and, consequently, of the bevel gear 43 forming one end of the differential. If the hand-wheels are rotated a certain amount and stopped, the gear 480:.

will rotate the spider a corresponding amount. Upon rotation of the shaft 50 of the hydraulic amount of movement of the hand-wheels. If-

, '6 I the hand-wheelsand the gun are-moyingat the same speed; the tilting. box will remain in a particular position and the gun wilLbe elevated or depressed at a speed corresponding to the, movement of the hand-:wheels- In order for the B end of the hydraulic gear to attain a particularveglocity in;accordance with the movement of the hand-wheels, it is necessary that the gun lag behind the movement of the hand-wheels. If the hand-wheels are rotated beyond a certain amount in either direction, the operation ofthe tilting box will be effected by the hydraulic gear. through the limit stops. i

v rh zimir tops The limit stops'act mechanically upon ,the shaft [8. As shown in Fig. 6, the shaft; [8 is reduced in diameter justbelow the rack so that cured to the block 59 and engaging the threads of the screw shafts 60 and 6| respectively. Adjacent the upper. end of the screw shaft 60 there is a spur, gear64 secured toqthe shaftfor rotationtherewitn'wA similar gear 65 is secured tothe shaft 61. These two gears both mesh with .a gear 65 mounted on a. vertical shaft 61 which is alsoyjournaled in the frame 41:. The gear 66 alsomeshes with a gear 68 secured. on the end of a vertical shaft 69 journaled at its upper end in an extension of the upper member of the frame 41. The lowerend of the vertical shaft 69 carries a bevel gear 10 (see Fig. 8) which is secured thereto for rotation therewith and which meshes with a bevel gear ll secured on the end of a shaft 12 which extends through and is journaled in the sides 13 and, 14 ofithe casing of the intermittent gear 29. i r

The intermittent gear 29 isan instrumentality by which a constant input effects an intermittent output at a speed equal to the input. That is, if the input shaft is rotated continuously, the output shaft will commence rotating only after a definite predetermined number of revolutions of the input shaft from any given relationship of the parts, and at a speed equal to the speed of the input shaft. In the intermittent gear 29 the input is taken off from the shaft 53 which as heretofore explained is connected to the shaft 50 of the B end of the, hydraulic gear. After the shaft 53 has rotated a definite predetermined number of revolutions from a givenstarting position, the shaft 12 rotates and through the beveled gears 10 and rotates the shaft 69.. Rotation of i the shaft 69 causes, through the gears 68, B6, 65 and 64, rotation of the screw shafts 60 and 6 I. Upon rotation, these shafts cause the block 59 to move. vertically along the shaft l8 and engage one or the other of the shoulders [8a or 18b. The direction of movement of the block is such as to move the rod [8 in such direction as to return the tilting box of the hydraulic gear to the neutral position. When this has been done, the B end of the hydraulic gear can not be rotated further in this direction. Suitable provision is made to allow of the backward rotation of the gear 48 and connected ;parts.when the rack I1 is operated 19. The valveconsists of a casing which is divided into three chambers; 11, b and c by, a'horizontal partitionIeB, and a vertical partition; I09. Each .of thephambers a and b communicates withthe 'chamberjc, through openings in the wall I 08. .'he opening between the chamber a, and the chambertc is normally closed by a poppet-valve H0. The valve is resiliently urged to the closed [position by arspring III which abuts against the valveat one end and againstthe plate H2 at :the other end. The plate H2 is mounted upon a rod I ls which extends through the bottom of a, plate II4. On the rod II3 there is a collar H5 which abuts. against. the upper surface of the plate IM. .A similar valve with a similar arsure of the pump. If, however, the pressure ex- :ceeds this, the valves will open. This isthe position of the valves when thehydraulic control is in operation.

The force exerted by the springs- III and III may be lessened considerably and is lessened'for the purpose of hand operation. This is accomplished by shifting a lever H3 mounted adjacent the hand-wheels I5jand I6. The lever H6 is secured to a shaft II'I journaled in transverse members 3Ic and 3 Id extending between the side frame members 3| a and 3 lb (Fig. 4) This shaft also carries secured thereto a pair of spaced arms H8 and II9 forming a dog for operating the clutch 39. The clutch has therein a circumferential groove in which engage pins I and I2I, extending inwardly from the arms II B and H9 respectively. The clutch is splined upon the shaft 31 for longitudinal movement with respect thereto but restrained against relative rotational movement. A spring I22 (Fig. 2) urges the clutch into the engaged position.

When the hydraulic control is being used, the clutch" is restrainedfrom moving into the en gaged position under the action of the spring I22 by a pin I23 which engages the lever H6. The pin I23 extendsthrough a cylindrical housing I 24 mounted upon the transverse frame member 3Ic. Adjacent the end of the pin I 23 which engages the lever IIG, there is a collar I25 which forms anabutment for one end of a spring I23 mounted in the housing I23 and abutting at its other end against ashoulder; therein. The pin I23is slidable within the housing I24 longitudinallythereof and at its opposite end is provided with a cross bar I2! by means of which it may be moved out of engagement with the lever II fixagainstthe action of the spring I26. When thisis done, the lever I I5 moves to the right as seen in Fig. 2 under the influence of spring I22'and the clutch; 39 becomes engaged.

A lever I 28 secured on to the shaft H! extends radially therefrom. This lever carries at its end a block I 29' through which the end of a rod I33 extends. The rod I30 has acollar I3I thereon which abuts against theyblock I29. The oppositeend of the rod I30 is pivotally secured to one end-of alever; I32 which is'pivotally mounted between its ends in a transverse jrame member 3Ie, The other;;,end ,o'flthe lever {the casing and is slidable therein, and through ,10 I32 is pivotally secured to a -link I33 to which is secured theplate l l4 through which the valve rods H3 and H3 extend. A link I34;i s pivot ally secured atone end to -.the transverse f ra me member in which the lever I32 .is pivotally mounted and at .the other end it ispivotally secured to the link; I33. This additional link provides a straight line movement of .thelink I33. It will beobserved thatwhenlthezlever, H3 is released and the ,clutch 39.is permitted :tO engage, the pressure onv the'collar. I3I bathe block I29 will be released and the plate tummy lmove downwardly thus relievingthe vtensionfloif the springs III. and III'.' The holes in the plate I I4 -for the valve rods I I3 and I I3 will provide the necessary loosenessto allow of the slight rela tive lateral movement of theplate. due to the arcuate. movement of its pivots. r The hydraulic connections, to .thecyli'nder 20 are illustrated diagrammaticallyin Fig. 11 1.;,'I'h e upper chamber of the cylinder is connected through a pipe line I 35 to the valve block; 26 in whichthere is included a piston valve for controllingthe supply of oil under pressure to the upper chamber of the cylinder. The valve block is mounted in the box I00 in which the pump is mounted: :The upper end of the cylinder is also connectedthrough a T-fitting I36 and by t pipe I31 to thechamber a of the valve ,III'IL. The lower chamber of .the cylinder is connected througha, pipe I33 to the high pressure side of the pump and through a T-fitting and a pipe I39 to the chamber b of the valve [01. The high pressure side of the pumpis also connected through a pipe I40 to the valve box.-, The cham-. her 0 of the valve I0! is connected througha pipe I 4| to the intake side :of the pump to which there is also a connectionthrougha pipe M2 to the valve block. It .will be apparent-from the connections illustrated diagrammatically in Fig. 11 that both the upper-andlower chambers of the cylinder 20 are connected to the lowpressure side of the pump throughthe valve-box I07. The pressure relief valves in ;the valve box have a dual function. I When the hydraulic gear is operating and controlled hydraulically, .the relief valves are under a heavy spring tension. However, if the hydraulic gear runs against- 9. limit 'stop and the tilting: box and piston IS are moved bythe force ofthe hydraulic gear to a neutral position, a high pressure would b e created in the cylinder 20. This pressure is, re.- lieved by the pressure relief valves-in the valve box I01. control is effective, the light tension on the springs provides a ready escape of the oil to the low pressure side of the pump, .thus, in effect, short-circuiting the pressure and rendering the hydraulic control ineffective. 3

The operation of the piston! in the cylin der 26 is accomplished bymaintaining pressure on both sides of thewpiston.- It will be noted that the. high pressure side of :the pump is directly connected to thelower chamber of the cylinder. The surface area of the piston upon which this pressureacts is, however, approximately one-halfof the surface area ofthe opposite face of the piston. Consequently, the same pressure in the upper chamber would create a force twice as great as the force created by the pressure in.the lower chamber When, however, the pressure in the upper chamber is relieved, the pressure in the lower chamber. causes the piston to rise in the cylinder. Withthis are rangeme'nt, the movement of the tilting boxjcan On the 0ther-hand,-when ,the hand I itiil in a."

' 1 1 accomplislied fiYFCOhtioll-iiig the? conmem er "c-l'i'amber to the high pres v e east, f"; s centre is fieftive th'rpuglf the piston {H3 in tlie valve block-2'6 (see Fig-L13). pressure is supplied to the valifebox e"pipe -'I4II which ceinmunicates -with rse pe's'sa'ge "I (Win-the valve block? The "It' lcommumeates witn the passage- I45 tends betweem an annularport I 46 sur=- fei' mite p p constent pressure valve niounted i'n-- the; valve blocl and ed or fiep irposeof maintai'ning tl'iehlg-h smear-e "et at constant pressure of; for exampi ,approxixnatelir fibfl -llist-per squareinch; The

iii 5914 ?communieetes with passage- I49" in tlge valve .block. passage?extends vertically v iigfi's'tl'i'e vailveilileel andconrrr'i unicates-. with part I51?surroundingthe piSton-fvttlvei The "n Vflve IB iS OT the usualty e iIY that it reduced" central portion Iflq; which: is deflated upon movement-'ofth'evalve tbleip either we higfi press-weep the exhaustlport;

d The circumfrential chaimber 'forrned by' reduihg the" valve" diamete'r communicateswith iiii perchanifier oi? the' *cylinde'r 20-? As viewed 1 it WiHbe apparent that'when H3 1s mVed tdi the left the cI'ia'mBefOf" the cylinder will be placed ommunicatifim with tlie high pressure; and the" v'ali'ieis moved t o the right theupper tii'ecyliiitlen will be placed into zoom- The length" of orti 'te these-tw'o positions and: in: the

pdsiuon illustreted in F181; 13 both their high exhaust ports ure cut off' 'from :comewee tIie up'per chamber of the an s teivei'jns ie snirtewte comm 13118 60111 cationiwith tlieupper chamber of the cylinan he higE'pres'sure=or 'exhaust by what termed an" hydraulic amplifier. hydra 11c amplifier is' operated throng-hi a.

put e1te-; f5a "when is provided with: a; rod, 'I 54 I 55; extending from each" end thereof ted in" plunger I5Iiw1'iich acts upon oil substantially closed" system connecting a cfi a'dmfieifforrned at one" end of" the plunger? with rmedait'oneend of the valve I43 frnej i e controls themovement of the which 'upon movin'g varies-the .pr'essure iittlie closedsystem': I

I A low-pressure"supply of oil;100.1bs; perisquare inch, is provided fonthepurpose of operating tlieiplunger-ilfl. 011" at this pressure" is" suppheubye reducing valve I51; having a port I58 ca unicatingw-ith thepassage In. There-- ducing valve consists of a' -piston' having a spring vI 5 Qiactiiigorione end thereof; the force: of which is regulated" so that the valve supplies therequisltepressure. A longitudinal passage ISO in tlie'ipiston" communicates with a, transverse passage IIiIi' When the pressure of"the= 0il= in: the passage I 60 isreduc'ed below 100 lbs;- pen square inch). the spring I59 causes-'- the piston I51 to niovei to theleft, as shownin Fig. 13. Upon movement in this direction; the transversepas I V 1 a'ced-into-' communication with the port? 58 a dpfl at- 600 lbs; per square inch is permitteii w enter th'epassage mm which com:-

alv'e I43 and an annular the actin of the spring I591 andthe' ttansveifse passage I6I is pl'a'cew inw commumcetion with v j the? exhausti ort I53 until the pressure? iir tl-ie pa s'sa'ge 'I sous reduced-"so' that tlie spring' moves the pistbrf I58 the left and thepassage-m is cut off from communication with tl'ie port I, g

'rne pbrtu 6-2 communicateswith-a; passaet! which communicates witl t-a' chamber I 6 5 forme't'i at -tlie= left hanti fendi' of? th'e piston valve; I.

Tlie' passage- I fil ailso conimunicates with aicha me bei- I96 tormed at tne left liand endiof a plunger I5 1 and? supplies;- oil to: the pilot valve? I 53: for

whichi purposeit communicates with a port: I 68.

Port I68 is normally; in communication; within transverse passage 1 IGfl thrjough the pl'unger I 56', the plunger I 56" having a reduced portioni lfliz with which the port I66 and the passag'e 'l'69 communicate: Intl'ie position of 'thetparts sh own in Fig? 13 the= passage ISSin the plunger: I56 is cut ofi liiy the pilot' 'valve I53:- The pilot valve I 5'3 hastwo: rieciuced lportions I53a and'? I'53b.- A I common exhaust pass'age similar -to" the passage I Gris also: provided; in: the valve: block; This exhaiust passa'gei; extendsfrom th'e port l! I 49 to" a port I10 surrounding the piston lfl ofl thelcon stantpressureivalve:

V Thea-constantv pressure valve is S'lmflarf'tOl the reducing. valve in. that": it: contains a. piston shawing at longitudin'ali central passage III and a transverse: passage I122 and a spring Ma -acting upon2:thea=pistonwith: a; constant 'pressure: One

end: otfizth'e passage IIEHI n the piston communicetes with the .port I41 through:a passage;-I 'll.

The: passage; I121: is: adj acentw the: exhaust port I70 and; whenltfie? pressure: in. the passage ITII exceeds1x60(l:-lbs:.. pen-square inch 1 the piston" 8 moved to the: right i gainst thesactiorr'of the spring: I T32 and: the :rp'a'ssage: I I2ian'd thevportr I10 are; placedii in: communication"; until thepressure isrrediiced-to:600i1bs1per square inch;

The exhaustpassagezextendsz throughtlre bldck and communitates-"withxthe port: linsand azport I15 surrounding a reducediportioni I'56b3of the pliingerl- I56". transversezpassage I15 extends through the:plunger?andcnormaily communicates with" the: exhaust port This: passage; like the: passage?- I69; is cut." on byrtlie' 'rpilot valve in the positionlshown' insthe drawingsv The re:- duc'ed: section I532; of. the: pilotvalve I53; forms a chamberf'whieh :v communicates: with. a r passage ITIIZJ'WHI'ICIiiiS a. branch of:a passage :IIII: extendiingtlongitudina'lly of; the plungerr and openin'gat the: end? of 1 the plunger: to achamber" I18" formed between the end of the plunger. and: azcapt I119. The passage; I 11 also. has "a; branch: passage?" I 1117 which communicates withthe chamberformed by." the" reduced portion I53b "Off the. pilot valve: 'Ihrough" these several ports! and. passages; the chamber:- I18: maywbe placed into? communication with either the intermediate pressure'wor the exliaust; v For example; if :the pilot valve is' moved to the left from the position: shown'in' Figr'. 13'; the passage I69-wil1 communicate with-the. passagee'l l'lb through the chamberiformedz by" the reducedrporti'on; I'53b' of" thei=pilot valve: 011 at the-.2. intermediate pressure will" therefore pass through thezipa'ssa'gei I IT into thechamber IIB". It" the: pilot: valve, 5 on: the other hand; is: moved toi-th'e -right from: the' position shown in" Fig; 13'; theepassagei I16 which communicates with: the exnaiust wili be pl'alced into communicatioirrw-itii the chamber formed by the reduced portion 153a of the pilot valve and through the chamber and the, passages I 11a and I", the chamber I18 will be placed into communication with the exhaust. I Movement of the plunger I56 in response to movement of the pilot valve acts upon and affects the pressure of the oil contained in a closed system of chambers and passages. This system includesa chamber I80 formed between the left-hand end of the plunger and a cap I8I, a port I82 communicating with the chamber I80, a passage I83 communicating with the port I82, a chamber I84 formed between the right-hand end of the plunger I61 and a cap or end-piece I85, and a passage I86 which communicates with a chamber I31 formed between the right-hand end of the piston valve I43 and an end cap I88. The pressure in this system is, in the neutral position of the plunger, that is, the position shown in Fig. 13, approximately one-half of the low pressure or 50 lbs. per square inch. In the position shown, the pressures in the chambers I18 and I80 are balanced. Upon movement of the pilot valve to the left, how ever, the chamber I18 is placed into communication with thelow pressureand the pressure in the chamber H8 is increased. The plunger thereupon moves .to the left and thus decreases the volume of the chamber I86. The necessary consequence of such a movement of the plunger is an increase in pressure in the chamber I89 and the passages and chambers to which it is connected, principally in the chamber IB'I. It will be noted that the surface area of the end of the piston valve I43 forming one end of the expansible chamber I65 is approximately onehalf of the surface area of the end of the piston forming one end of the expansible chamber I81. Consequently, an increase in pressure in the chamber IBI will cause the piston valve to move to the left and thus place the upper chamber jof lthe cylinder 2%} into communication with the high pressure. t I

If it be assumed that the pilot valve is moved to the right from the position shown in Fig. 13, and the chamber I18 placed into communication with the exhaust in the manner heretofore explained, the pressure in the chamber H8 will be reduced and due to the pressure in the cham- .ber I60- it will move to the right following the movement of the pilot valve. Thus, the volume of the chamber I60 will be decreased and the pressure in the closed system of which the chamber forms a part will be correspondingly reduced. The result of this reduction in pressure, in so far as the piston valve I43 is concerned, is that the total force exerted by the oilinthe chamber i65 will exceed the total force exerted by the oil in the chamber E8? and the pistonvalve I43..will be moved tothe right. Thus, the upper chamber of the cylinder zfi will bevplaced into communication with the exhaust passage I50. It is to be noted that the plunger I56 follows the movement of. the pilot valve. In" practice the difference in movement of these two elements is imperceptible. In viewof this action; the valveand plunger tend to retain the same relation as that illustrated in Fig. 13.

The valve mechanism just. described, if unmodified, would operate so asxto cause a movement of the piston 19 inthe. cylinder 26 which "would not bedefinitely related tothe movement of the pilot valvel53 since the piston valve I 43 would remainopen-when the pressures in dzhmchambers I8! and- I65 were. equalized by ,14 movement of the valve I43. I The action is, therefore, modified so that the piston I9 is returned to the off-position on the completion of a definite movement of the pilot valve, and, consequently, the movement of the tilting box is proportional to the movement of the pilot valve. This is accomplished through the action of' the plunger I67 which forms withthe plunger I56 and the valve 543, acting in the closed system, a hydraulic diiferential in which the movement of the valve I43 is the algebraic sum of the movements of the plungers I56 and I61. Like the piston valve 153, the plunger I61 hasend faces of different areas. The end face forming one side of the chamber I66 is approximately half the area of the surface extending into the chamber I84. Thus, in the normal condition the resultant force on this plunger is equalized. The surface area of the end of the plunger and the chamber I66 is cut down by a rod I89 which is integral with the plunger and which. extends through the cap I66 forming one end of the chamber I66. The end of the rod I89 is pivot-- ally secured to one end of a link I9I' (Fig. 3), the other end of which link is pivotally secured to one end of a lever I92 which is mounted upon and secured to the shaft 25 extending through the casing of the hydraulic gear and which rotates with the movement of the tilting box. Thus, the plunger I67 is moved to the right or to the left depending upon whether the piston I9 is moved upwardly or downwardly. Since the piston I9 moves downwardly when the piston valve I43 is moved to the left, the plunger I51 will also be moved to the left and conversely, that is, the plunger I6? is moved through the action of the tilting box in the same direction as the piston valve I 43. Movement of the plunger l6! changes the volumetric space of the closed system. The result of its movement in the same direction as the piston valve is that it increases the volume of the closed system when the plunger I56 acts in a direction to decrease thevolume, and when the plunger I56 moves in a direction to increase the volume, the plunger I6! is moved in a direction to decrease the volume. That is, its tendency is to offsetthe effect of: the movement of the plunger I56. Therefore the plunger I67 responds to the movement of the tilting. box and restores the balance on the piston valve M3. The plunger I6? is therefore denominatedv a response plunger. It will be apparent, however, that movement of the plunger It? is dependent upon movement of the tilting box so that upon movement of the plunger I56 the pressure in the closed system is increased or decreased and this increase or decrease remains constant for a space of time. in otherwords, the movement of the plunger I6? lags behind the movement of the plunger I56, the'lag being occasioned by the fact that theplunger I61 is moved by the tilting box; However, upon. movement, the plunger tends to and does ultimately reestablish equilibrium with the valve I43 in the position shown in Fig. 13. The result is that if the pilot valve is moved in either direction a definite amount and then held in the position to which it is moved, the tilting box will be moved through an angle proportional to the movement of the pilot valve and held in that position. This would be equivalent to a re- .sponse' to a signal requiring movement of the gun at a constant velocity.

With the arrangement described, there is necessarily a phase diiferenceor velocitylag of is;provided;v thereior.e,;, in; the. system. a." means font-removing thealag; This consists of atcoma municatiom between. the intermediate: pressure onenhaust-and therclosed; system acting between theaplunger: LG; andzthei. piston I43. .Thiszcommunicatiorr. is: througha port}; I93; a passage H431. a: needle. valve I.9;5 and. a. passage? I86. The. [93: is: placed. inf. communication. with:

, thee-exhaust; portr- I;I5 or: the. intermediate: pres.-

s-ure'e. port; I.-88- depending upon the. movement of;theplungexrv I156 If .the plunger I 55 is:. moved torthe leftrirom. the; positionillustrated inE-ig.v 13;; the; port I93? is placed in communication witlnthe:intermediatepressureport. I88: and oil flows from-the: intermediate.- pressureport. I68 through: the, passages, I.94;, the needle: valve I95. and theapassage; I96 so; as to. increase the. pres.- sure' imth'e passage I83; On the,- other. hand; thelplungerr'moves to. the right, thepassage I883. is;- placed. into communication. through? the needle; valve; with the. exhaust. port I I5. Thus, thecommunication. with the. passage I83 through the needle; valve. is; such. as, to. augment. the efl'ect'zof; the; movement of the? plunger: The needle: valve isaad-justableand;.is= set: in such position: asigiveslthea best results. The result is that the: pressure :-.in. the. passage I 83:, and the closed system augmented: or: decreased; gradue 21133:. Theipiston. valve. I43 is thus. moved be.- yond i the point to. which. it' would. otherwise movedil unorrmovement; of theapilot .valve. Thi'snadditionitl; movementzcauses the; hydraulic gear-to. assume: a: velocity in: addition. to. that which; is proportional; to .the movement. of; the va'lvez. This advances; the; gun into. syn-. chronisnrwitht the: signal. Oil... passing through 'therneedlivalve: also maintains. the: oil. in the;

closeisystematthe proper: volume. The needle valve must: besadjustedzempirically in. each partticularr: system.

Under: extreme; conditions of acceleration. the

' pilot:- valve and; consequently: the: plunger. I56

may: be moved;.rapidly from one extreme... p0;- sitiorrto therother; 'Io guard; against. any; of the spartsrassuming: .aposition from which they could: not: be; moved, there: is: provided. certain limiting; ports. and... passages.- In the plunger I58? two: such 1 passages. are. provided. I91 and I985. The passage; I9]- extends between: the passage;:- I89. and: a. transverse. branch passage I91 a; .the'abranch" passageextendi'ng: between; the passage: III'I. and. the; circumferential. surface. of the plunger." I581 The passage I98 communicates: with. the chambers I80 through the end of the. plunger" and a. branch passage. 38a

which". extends." between; the passage I 98-: and. the v surface: of: the plunger: The; passage I910,- is so 'located that} if" the plungerl58. is moved to thedeft from the positionillustrated in. Fig; 13', untilaithe end; thereof is adjacent-the cap: I8I,

"I IiIIi In; thisi-conditiom. oil under; the.' low: pressure wiillbetadmitteri; toatherport: I8 2:. antbnmve "the passage. 191a: will. -be in; communication I with the port I82 and;also:.the'zlowpressure port is. covered. omthe other hand ifl the: pressure inrthe chamber I88.- becomes such. as,-t'o. force the-plunges to: the; right. against. the cap; I19; the. passage I98a. will. communicate.- with. the exhaust. port- I15. and thus exhaust oil. from theachamberl. L88; The oiliirom. the..chamher I88:- will. be. exhausted. until; the: pressure. in..the chamber I18. is suflicient. to. move the. plunger. to; the left. a distancesufiicient. to. cut off the communication. between. the. passage. I.98a. and the exhaustporh I.'I5,.

Similar ports. and passages. are provided. in the. plunger I6I and\ the valve. I43... Inthe-sur face. otthe. plunger I.8I there is; formed. a cut indicated: at. I.B=Ia out. is. suchthatq. when.

theplungen'is moved asuflicient distancato right. from. the position shown. in Eig, I3... the chamber. I84. will be placed. incommunication with. the.v chamber L88 so thatv oil, under. press sure. will. pass from. the. chamber. I68 through the. cut J 510. and intorthe. chamber I84; When. theplunger. I81. is. moved to. theleft; asufiibieht distance: it uncovers. aport, Ififlb which. places the. chamber I84. into communication with..the exhaust. 'Ihe. piston valvehas. a. longitudinal central. passage. I431). which communicates: at one, endwith the chamber. I 65 andat weather end. with a...radial passage. mac. Upon move.- ment. of. the: pistonsvalve. at suflicient. distance to the right, the passage. I432 communicates through; agroove or port. I8'Id with. the chamber I81 and thus-.connectsthechamber I81; to. the chamber 55.. Upon movement of. the piston valve. to, the. extreme. left. an. L.-shaped'. passage I43d. comiects the. chamber. [.81 to. the. exhaust port- I5I... These limiting. ports. and. passages also establish. the. volume: of the. out inthe' closed system..

The. various. ports and. passages? are related to the. oil' pressures. existing. therein. as; indicated by the: legend. at. the..l'o.wer. end of. the. drawing containing Fig. 13. In this legendthelollowing abbreviations are. used:

EXT-Exhaust! H. P.-Highpressureror...thetpressurezofifilloilbsz per-square inch H. P. and.EXI-I;High pressure and exhaust; or

cylinder pressure L. P."-Lowq.pressure :"or the? pressure of 100 lbs.

perfisquar e inch L..P..:.an'd pressure .andexhaust; L. P.0'ne-halfii of thelow pressure or? 58; the. per square inch.

Automatic operation:

The amplification 1 of the hydraulic: arrange:- ment in the valve block is such that: therhydrauli'c-gear is" responsive to the least force onthe valve rod I54 or- I55. Because of? this. sensitive:- nessthe-system maybeoperated: directlyv from receivers of a selsynsystem. In the automatic operation of the system,-the pilot valve ist-Lunder the;.jointz control of the. two Selsynreceivers 21. and. 281 of. a. Selsyrr system. The: receivers 17 winding of the rotor of a transformer 20I. The stator of the transformer 20I is connected to the stator of the Selsyn receiver 21. The rotor of the transformer 20I is rotated by a shaft 202 which represents the angular amount by which the rotation of the shaft I99 must be modified because of other conditions, and the transformer in eifect adds or subtracts the rotational movement of the shaft 202 to or from the rotational movement of the shaft I99. The output which is connected through gearing 2I0 to the shaft 202 which operates the rotor of the transformer 20I. The ratio of the gears 2I0 is such that the shaft 209 rotates thirty-six revolutions for each revolution of the shaft 202. The stator of the transformer is connected to the stator of' the receiver 28 so that the output of the stator 28 is related to the output of 'the receiver 21 as thirty-six is to one. The receiver 28 acts in the nature of a Vernier to provide a fine adjust- .m ent of the pilot valve in accordance with the signal as represented by the receiver 21.

Rotational movement of the rotor of the receiver 28, relative to the movement of the gun,

is translated into longitudinal movement of the pilot valve through a cam and lever arrange-' ment. The receiver is secured to the plate I02 in the position shown in Figs. 9 and 10. On the shaft of the rotor of this receiver there is mounted an L-shaped'bracket 2| I. One arm of the bracket 2IIa, is secured to the end of the shaft and extends perpendicular thereto, and the other arm 2| lb of the bracket extends parallel to the shaft, offset from the axis thereof, as best shown in Figures 14 and 15. The arm 2| II) is bifurcated and between the arms thereof there is pivotally mounted a lever 2I2 which carries on one end a ball cam follower 2I3 and at the other end a cam 2 IA. Pivotallymounted on the same pin on which the lever 2I2 is mounted there are a pair of levers 2I5 and 2I6 which act conjointly. The free end of the levers 2I5 and ZIG are secured together-by a pin 2|I and they act as a single lever. A lever 2 I 8 is pivotally mounted on the pin 2| 1 at one end and at its opposite end carries a rotatably 'mounted cam follower 2I9 which engages the cam 2I4 on the lever 2|2. The cam 2M is in the nature of a constant rise cam. At its center it is provided with a notch.

2I4a in which the cam follower .2I9 normally rests. against the cam face 2M by a spring 220 which acts between a bar 22I extending across the levers 2I5 and 2I6 and a flange formed on theend of a branch arm 2I8a of the lever 2I8, the branch arm 2I8a extending at right angles to the arm 2 I3. As this lever 2I2 is swung about its pivot, the engagement of the cam follower 2I9 and the notch of the cam 2I4 will causethe levers 2I5 and 2H5 to follow the movement of the lever 2|2. The valve rod 155 of the pilot valve is secured to the pin 2 I1, and it is reciprocated in accordance with the movement of the. levers 2I5 and 2IB. 3

The valve rod I55 extends through a hollow The cam follower 2I9 is normally urged 1Y3i extension I56c-(Fig.13') extending from the end of the plunger I56 a'n'd through the cap I19;

through a cylindrical mounting 222 (Fig. 15) secured to the side of the box I00 and upon which acam 223 is rotatably'mounted. The cam 223 is provided with a' circular roove 224 which is eccentric to the axis of the cam 223 and the rotor shaft of the receiver 28 and which receives theball cam follower 2I3 on the lever 2|2. The'cam and. a gear 225 to which it is secured are were of the receiver 28 is rotated, the arm 2I2 will be moved about its pivotal connection tothe bracket 2| I an amount proportional to the relative movement of the rotor shaft. This movement of the arm 2I2, through'thelinks and levers previously described, will effect longitudinal movement of the pilotvalve I 53.

the-end of the extension I5Ec. This spring is for the purpose-of taking up anyslack in the assembly. 1 i I The gear 225 is in mesh with a gear 228 (Fig. 10) mountedupo'n a shaft 229journaled in bearings secured to'theplate I02. On the end of the shaft 229, there is secured a gear 230 which.

meshes with a gear 23 I mounted upon a stub shaft 232 (Fig. 2) The gear 23I is also in mesh with a gear 233 securedfon the shaftof the B end of the hydraulic gear (see Fig. 16). The gear- 225 is thu rotated in accordance with the rotational movement ofthe hydraulic gear. The gear train connecting the gear 225 to the shaft of the hydraulic gear is such that the gear 225, and, consequently, the cam'22j3; is rotatedat a speed'which is commensurate, with a ratio of thirty-six to one to'the gun. It is' also'rotated in the same direction as the rotor shaft of the receiver 28. Thus, it is the relative movement between the gun and the rotor shaft of the receiver 28 which effects movement of the lever 2I,2 and consequently of the valve I53..

It will be noted that the cam groove 222 in the cam 223 is continuous and consequently the gun and signal may get out of positional agreement or synchronous operation. If, however, the cam and the rotor shaft of the receiver28 are out of positional agreement by an angle of which represents a few minutes of angular difference betweenthe gun and the signal, the'receiver 2'! takes over control of the pilot valve. This is accomplished through a solenoid 234 (Figs. 9 and 10) which is mounted upon an extension I5Ed extending from the end of the plunger I55 and through the cap I8 I. The solenoid acts upon the valve rod I54 to operate the valve. The solenoid has directional characteristics and is energized through stationary electrical contacts 235 and 236, and a movable contact22'I which is mounted between and cooperates with the stationary .con tacts 235 and235 (Fig. 9). The stationary contacts 235 and 23 5 are mounted upon brackets extending from a plate 238 secured to the plate I02. The movable contact is brought into and The i a valve rod also extends through the side of the. box I 00 in which the valve block is mounted and A spring 221 surrounds the rod I55 and abuts'against the pin 2II and against 21 hydraulically operated valve for controlling the application of a hydraulic medium to the hydraulically operated element, and actuating means for the valve comprising a closed volume hydraulic system formed in part by one end of the valve, a plunger operable to displace the hydraulic medium in the system in accordance with difierences in movement between the movable and driven objects, and another plunger, operable to displace the hydraulic medium in the system and actuated by movement of said movable element, the displacement of the hydraulic medium in the system being effectiveto actuate the valve.

4. In a control system for variable-speed, power-driven driving means having a movable control element adapted upon movement to effect changes in the speed of the driving means, the combination comprising means for moving said control element, control means for said control element moving means, actuating means for effecting the actuation of thecontrol means, and a hydraulic differential interconnecting the control element of the driving means, the actuating means and said control means.

5. In a control system for variable-speed, power-driven driving means having a movable control element adapted upon movement to eiIect changes in the speed of the driving means, the combination comprising means for moving said control element, control means for said control element moving means, actuating means for effecting the actuation of the control means, and a hydraulic differential interconnecting the control element of the driving means, the actuating means and said control means including a closed, variable-volume hydraulic system containing a hydraulic medium under substantially constant pressure, means for varying the volume of the closed systemin accordance with the movements of the actuating means, and additional means for varying the volume of the closed system in accordance with movements of the control element of the driving means.

'6. In a control system for variable-speed,

power-driven driving means having a movable control element adapted upon movement to effect changes in the speed of the driving means, the combination comprising means for'moving said control element, control means for said control element moving means, actuating means for effecting the actuation of the control means, a hydraulic differential interconnecting the control element of the driving means, the actuating menting the effect of movement of the actuating means.

i 7. A control for a variable-speed, power-driven driving means, comprising a movable element adapted upon movement to efiect changes in the speed of the driving means, manually operative means directly connected for efiecting movement of said movable element, a motion receiving element, power amplifying means responsive to said motion receiving element and adapted to operate the movable element, means for selectively rendering said manually operative means andsaid motion receiving element efiective for effecting movement of the movable element, and means controlled by the movement of the driving means and operative upon a predetermined movement of the driving means ineither direction to incapacitate the driving means for further movement in the same direction.

8. A control for avariable-speed, power-driven driving means comprising a movable element adapted upon movement to effect changes in the speed of thedrivingmeans'manuaHy operative means for effecting movement of said movable element, two motion receiving elements, power amplifying means responsive to either of said motion receiving elements and adapted to operate the movable element, means-for selectively connecting said manually operative means and said motion receiving elements to effect movement of the movable element, and means con trolled by the movement of the driving means and operative upon a predetermined movement of the driving means in' either direction to"inca pacitate the driving meansior further movement in the same direction;

9. A control fora variable-speed,- power-driven driving means comprising a movable element adapted upon movement to eiifect changes in the speed of the driving means, manuallyfoperative means for effecting movement of said movable element, two motion receiving elements, power amplifying means responsive toeither of said motion receiving elements and adapted to operate the movable element, means for selectively connecting said manuall operative means and said motion receiving elements to effect movement ofthe movable element, means for rendering one of said motionreceiving elements ineiiective upon the operation of the other, and means controlled by the movement of thedriving means and operative upon a predetermined movement of the driving means in either direction to incapacitate the driving means for further movement.

in the same direction. N

10. In amechanism fordriving an object in accordance with the movements of another,

object, the combination. comprising a movable object, a driven object, power-driven operating means for the driven object, a variable velocity transmission connecting the power-driven operating means and the driven object, means for regulating the variable velocity transmission including a member differentially connected to the movable and driven objects, andmeans con trolled by the movement of the driving means and operative upon a predetermined movement of the driving means ineither direction to incapacitate the driving means for further movement in the same direction.

11.. In a mechanism for driving an objectlin accordance with the movements of another object, the combination comprising a movable object, a driven object, power-driven operating means for the driven object, a variable velocity transmission connecting the power-driven operating means and the driven object, .meansfor regulating the variable, velocity transmission including a member difierentially connected to the movable and driven objects, manually operative means for regulating the variable velocity transmission, .means for selectively connecting said differentially operated member and said manually operative means for regulating the variable iielocity, transmission, and means controlled by the movement of the. driving means and operative upon apredetermined movement of the driving means in either direction to inca- "13. In} a. control system for variablespeed, power driven driving means. having a movable o'o' trol element adapted upon movement to'. effect. on rig es i'n speed of the drivingl'means, the comu its or a 'oontrol plunger,'a control piston va s and a respon se pmngene closed hydraulic system the chamber'of which includes'one end of each of the said plungers and piston valve, means" for maintaining a' normal pressure in the cl" e system'frneans for "exerting a balancing fo e n'the, opposite'endof the 'control piston equal 'to the force on 'thepi'ston valve of Se normal pressure, means operatively connect-' in the con 01 piston valve and the movable con i means 'operatively connecting the ramps; control element 'with the response plunger) and"m'eans 'for. operating the control i me ses?- e' sr a em t f h me in heclosed system,whereby a movement of the control plungendisturbs the balance on thepiston vaiveand the resultant movement of the response plunger restores said balance.

14 In a mechanism for driving an object in aceordance with theinovement of another ob- 'jectgtihe combination of a movable object, a driven object, variable-speed driving means for, the driven object having a movable control elea control plunger, a piston valve and a response plunger, a closed hydraulic system the oharnber of which includes one end of eachof said plungers and piston valve, means for maintaining a; normal pressure in the closed system, means for producing balancing. hydraulic pressures ontheopposite ends'of both thecontrol plunger and piston valve, hydraulic z'near'is under the control of the piston valve for actuating the control element, means operatively connecting. the'control element with the response plunger, a pilotvalve'responsive. to the relative movement or'the movable and driven objects operative to alter the pressure on the said opposite end of the control plunger and thereby cause the plunger t were nd enes the 'ms um i se i6. Inv hydraulic, renew-up. control means, for e ai'first"chamberifof"variable meausrcr faltering tn'eJvoIu cIiaifiberYoffWariabIeT volumetric capacity; means, active. to'aIterthevolumetric capacity of said sec- 0ndfchamberco'nformably with and responsive to operationloffthe controlled device, a third chamberl of variable". volumetric capacity, the vo1u-' metric capacity of said third chamber. being a1- tereufupon change involumetric capacity of said firstand seeond chambers, a control element arranged to moveresponsive to change in volu-l metric.,,capacityof said third chamber and active to. regulate the operation of said controlled .de:

vice, means connecting. said chambers with one another. to form a, closed hydraulic circuit and means arranged to maintain a substantially con- Stant.predeterminedpressure in said circuit dur-v ing the time that the volumetriccapacities of all of said chambers remain constant, departure from saidpredetermined, pressure in said circuit. being. accompanied by change in the volumetric capacity of said third chamber and said control element. being responsively moved in a direction to cause operation of; the controlled device in a direction and to an extent to effect corrective, change in the volumetric capacity of said second chamber to thereby restore the predeter mined pressure, in said circuit.

17. In control means for a power-operated de- V neutral position in which said power-operated cause operation of said power-operated device in.

the opposite direction, means for altering the pressure in said circuit relative to said predeter l mined pressure value and means responsive to operation of said power-operated device and active to correctively alter the capacityof one of said chambersto restore said predetermined pressure value in saidcircuit.

18 In control means for an hydraulic-poweroperated d vice, a closed hydraulic control circuit comprising. at least two chambers of variable volumetric capacity, means establishing a predetermined. pressure value to exist in all parts of said circuit including both of said chambers during. the time that the capacities of all chambers thereof remain constant, a, valveelement movable to control the flovv of operating pressure fluid to and the exhaust of fluid from said device to thereb control its operation, said valve element having. "aneutral'position in which said device is rendered inoperative and being movable, from said neutral position responsive to pressure in said circuitabove said predetermined value to eus igper uon of said device in one direction and movable responsive to pressure in said circuit below said predetermined value to cause operatron ot said device in the opposite direction,

111 ns f 'lteringtlie pressure in "said circu ffla nQs P BS va ue and 

